back up,Norton ghost/Acronis?

Starting to learn about backup for my PC,3 yr. old HP with XP...I do want an external HD but now I learn to actually "mirror" my HD I need something like Norton Ghost or Acronis true image?...I do a lot of raw image converting using canons Dpp,save as tff and burn to disc...I use only an older Adobe elements for further tweaking,works for me...I'm confused on what I actually need. I know I can save images,files on an external HD but whats best for recovering,as is, my PC's hard drive? Thanks for any help,old bob